Brain Pop
Besides strength what is
another physiological
role of the muscular
system?
Muscles
Muscles are combined with nerves,
blood vessels, and various
connective tissues.
• Muscles are quite complex and as
we’ll find out, they are a marvel of
both biology and physics.
Muscle Functions
1.
Production of Movement
– Movement of body parts and of the
environment
– Movement of blood through the heart and
the circulatory vessels.
– Movement of food (and, subsequently, food
waste) through the GI tract
– Movement of urine through the urinary tract
– Movement of semen through the male
reproductive tract and female reproductive
tract
– Movement of a newborn through the birth
canal
Muscle Functions
2.
Maintenance of posture
– Muscle contraction is
constantly allowing us to
remain upright.
– The muscles of your neck are
keeping your head up right
now.
– As you stand, your leg muscles
keep you on two feet.
3. Thermogenesis
– Generation of heat. Occurs via
shivering – an involuntary
contraction of skeletal muscle.
Muscle Functions
4. Stabilization of joints
– Muscles keep the
tendons that cross the
joint nice and taut.
This does a
wonderful job of
maintaining the
integrity of the joint.
Characteristics of Muscle Tissue
1. Excitability
 The ability to receive and
respond to a stimulus
• In cardiac muscle, the
stimulus could be a
neurotransmitter, a hormone,
or stretch.
Characteristics of Muscle Tissue
2. Contractility
 The ability to shorten forcibly when
adequately stimulated.
– This is the defining property of muscle
tissue.
3. Extensibility
 The ability to be stretched
4. Elasticity
 The ability to recoil and resume original
length after being stretched.
Skeletal Muscle – the organ
The whole
muscle is
surrounded by a
layer of
connective
tissue known as
the epimysium.
Epimysium surrounds
several bundles
known as fascicles.
Fascicles are wrapped
by perimysium.
Each fascicle is a
bundle of super-long
skeletal muscle cells
called muscle fibers
Muscle fibers
surround a layer of
connective tissue
called the
endomysium
(peri=around).
Skeletal Muscle –
the organ
In this photomicrograph, you should notice: the epimysium on the
left, the multiple fascicles, the translucent perimysium partitioning
them , and the multiple muscle fibers making up the fascicles.
Skeletal Muscle –
Blood & Nerve
Supply
Each skeletal
muscle is typically
supplied by one
nerve, one artery
and one or more
veins.
3 Types of Muscle Tissue
Muscle attachments
may be direct or
indirect.
Direct attachments are
less common.
Indirect
attachments are
typical. The
muscle extends
and forms either
a cordlike
structure
(tendon) or a
sheet like
structure
(aponeurosis)
Skeletal Muscle
Microanatomy
• Each skeletal muscle cell is known
as a skeletal muscle fiber because
they are so long.
They’re so large because the fusion of
hundreds of cells called myoblasts.
 Muscle fiber Plasma membrane is known
as sarcolemma
 Muscle fiber cytoplasm is known as
sarcoplasm
Physique- Exit Slip
Copy question
• Different athletic
activities require
different muscle
groups. How would
you expect the body
of a speed skater to
be different from that
of a kayak paddler?
Which muscles
would be highly
developed in each of
these athletes.?
The muscles contract due to a
continuous ready supply of
calcium and ATP.
Rigor Mortis
• Upon death, muscle cells are
unable to prevent calcium entry.
Since there is no ATP made
postmortem, the muscle fibers
cannot unbind and the body
remains in a state of muscular
rigidity for almost the next couple
days.
Working Muscle
• After the energy supply is depleted,
the muscles must find another ATP
source.
Anaerobic means “without air,” and
it is the breakdown of glucose
without the presence of oxygen.
Because of that lack of O2 supply
for aerobic metabolism= lactic acid
cause cramps.
Muscle Fatigue
Physiological inability for
muscles to contract
Results primarily from a
relative deficit of ATP
(energy).
Thought questions: why do chickens have
white breast meat and dark leg meat? What
does this say about the activities of the
associated muscles? Why do ducks have dark
breast meat?
Clinical Disorders
Muscular Dystrophy
(MD)
Inherited disease which fibers of
muscles can be damaged
Voluntary muscles become
weaker and connective and fat
tissue can replace the fibers,
resulting in inability to walk
Other Important Terms
• Spasm
A sudden, involuntary smooth or
skeletal muscle twitch. Can be
painful. Often caused by
chemical imbalances.
Other Important Terms
• Cramp
A prolonged spasm that
causes the muscle to become
taut and painful.
Other Important Terms
• Hypertrophy
Increase in size of a cell, tissue
or an organ.
• Atrophy
Reduction in size of a cell,
tissue, or organ
Smooth Muscle
• Involuntary, non-striated muscle
tissue
1.Cardiovascular system
2.Digestive systems
3.Integumentary system
4.Respiratory system
5.Urinary system
6.Reproductive system
Cardiac
Muscle
Striated,
involuntary
muscle
Found in walls
of the heart
Notice the branching and the
intercalated disc, indicated
by the blue arrow.